Corneal Thickness Variation and Consistency According to Daytime

ABSTRACT

To analyze the normal adult corneal thickness, we used the Orbscan(Orbtek, Inc.)to measure 50 volunteer subjects. The reproducibility of the pachymetry, the daytime variation of corneal thickness and the consistency of thickness across days were analyzed. All 50 subjects were measured, taken each at 800, 930, 1100, 1300, 1430, and 1600. The corneal thickness was taken at the center and 1.0 mm, 1.5 mm, 2.0 mm, 2.5 mm, 3.0 mm and 3.5 mm away from the center. Also measurements were made 3 consecutive days at the center, 2.0 mm and 3.5 mm away from the center. Repeatability of corneal thickness was highly reliable(Guttman split-half point0.9972 and 0.9961, respectively). The average distance difference was 10 micrometer at the center and 23 micrometer at 3.5 mm away from the center. The corneal thickness did show a diurnal pattern during the day but was stable when measured across days. No significant difference when measuring on the same hour on another day was shown the corneal thickness to be consistent.